1. Field of the Invention
This invention relates to a process of blowing high-oxygen gases into a molten bath which contains non-ferrous metals through double-tube nozzles, which extend through the reactor wall into the molten bath, wherein a protective cooling fluid is injected through one tube of each double-tube nozzle.
2. Discussion of Prior Art
In some pyrometallurgical processes of producing non-ferrous metals, high-oxygen gases consisting of commercially pure oxygen or oxygen-enriched gases are blown into a molten bath. Such processes are used, e.g., to extract nonferrous metals or matte phases enriched with non-ferrous metals from sulfide ores or to refine molten baths which contain non-ferrous metals. The high-oxygen gases are blown into the molten bath through nozzles extending through the brickwork of a reactor from the bottom or the sides thereof. A protective fluid is used to protect the nozzles and the surrounding brickwork from the high temperatures which occur at the nozzles. Double-tube nozzles are used for this purpose. In general, the high-oxygen gas is blown through the inner tube and the cooling protective fluid is blown through the annulus between the inner and the outer tubes. Such processes are known, e.g., from German Offenlegungsschrift Nos. 24 17 979 and 28 07 964.
Such double-tube nozzles and the injection of high-oxygen gases together with a protective fluid have been used first in the steel industry (German Patent Publication Nos. 15 83 968; 17 83 149; 17 58 816; 20 52 988; 22 59 276; 14 33 398; British No. 1,253,581; Austrian No. 265,341). Efforts have always been made to prevent formation of crusts on the nozzles because such crusts have undesired effects on the motion of the bath, the erosion of the brickwork and safety in operation. Only where water-cooled single nozzles are used is it desired to provide a layer of solidified iron or metal in order to protect the cooled portion of the nozzle tip from destruction. The previous uses of double-tube nozzles in non-ferrous metallurgy to inject high-oxygen gases together with a protective fluid (German Offenlegungsschrift Nos. 24 17 979 and 28 07 964; British No. 1,414,769) were obviously based on the same assumptions. But that practice results in a considerable wear of the nozzles and the surrounding brickwork.
It is an object of the invention to reduce or avoid the wear of the double-tube nozzles and the surrounding brickwork in processes of blowing high-oxygen gases and protective fluids into molten baths which contain non-ferrous metals.